In a conventional internal combustion powertrain vehicle it may be desirable to output positive wheel torque to hold the vehicle at a standstill condition. This condition may occur, for example, when a driver attempts to hold the vehicle position at a standstill on an incline using only the accelerator pedal. The powertrain may include a torque converter which allows the engine output shaft to spin while the drive shaft remains still, until sufficient torque is transferred by the fluid connection of the torque converter to move the vehicle forward. Also, the fluid connection of a torque converter allows the engine to spin at vehicle standstill without causing substantial wear on powertrain components.
A disconnect clutch can also be used to vary the torque transferred from the engine to the drive shaft. For example varying the clutch pressure in order to “slip” the clutch can vary the amount of torque transferred to the drive shaft. However slipping the clutch can increase clutch surface temperature and in turn affect clutch durability.